Is "Survival Of The Fittest" A Tautology?

Some people have suggested that this famous phrase is a
tautology - that is, of the form "an X is an X" and therefore
pointless. If it just says "Survivors survive", then the complaints
are right. There are three rebuttals:

Rebuttal #1: Who Cares

Charles Darwin never used this phrase, except to complain about it.
It isn't used in my favorite biology textbooks.

The Theory of Evolution has never been about survival. What Darwin
said was that heritable variations led to differences in reproductive
success. Philosophers of
science agree that that's not circular or tautological.

Rebuttal #2: Let's Define Terms

There are several possible definitions of "survival". If we use a
definition which includes leaving a relatively large contribution to
the next generation, then we have more or less what Darwin actually
said.

Rebuttal #3: Is It Obvious?

If a phrase isn't obviously true, then it can't be a tautology. Did
anyone ever seriously argue that the poorly designed shall triumph?
Well, yes, quite a few people did. Darwin wasn't the first scientist
to try to explain all those extinct species. Many of the rival
theories asserted that the fittest must perish.

For example, Alpheus Hyatt claimed that lineages, like individuals,
had cycles of youth, old age, and death (extinction). Decline was
programmed in. As maturity leads to old age, the best individuals die,
leaving the worst to see the end.

And there was the theory of orthogenesis. It held that certain
trends, once started, could not be stopped, even though they led to
extinction through increasingly inferior design. For example, Irish
elks had enormous antlers. It was held that they had died out because
they were unable to stop the size increase. Likewise, the demise of
saber-tooths was supposedly because their teeth had gotten longer and
longer, until the poor creatures couldn't open their jaws wide enough
to use them.

So, "Survival of the fittest" was apparently not obvious until
after someone pointed it out.